Conventional studies have been carried out related to sound field reproduction method. Regarding speaker reproduction, surround reproduction such as 5.1 ch. and 7.1 ch. is generally proposed and is commercialized. An advantage of this technique is to use speakers called rear surround sound speakers, as well as front speakers and in combination they are capable of reproducing rear and environmental sounds.
However, a problem arises during the surround sound reproduction to find the best ideal sound field point for listening in a service area of the installation center, of which is limited. In addition, in surround sound reproduction, there is a problem that it is difficult, to arrange the speakers in a rear position in an actual home.
As a measure to solve the problem concerning the speaker arrangement, there is a front surround speaker using a transoral technique. In the front surround speaker, virtual surround sound can be enjoyed by using only the front speaker and using a head-related transfer function. The advantage of the technique is that the speaker can be easily installed and the system is simple. On the other hand, there is a problem that individual variations in the effect may occur because the head-related transfer function is used. In addition, also in the technique, there is a problem concerning the listening position that the ideal position for the reproduction is limited.
As a measure to solve the problem concerning the listening position, there is a sound field reproduction technique using wave field synthesis (see, NPL 1). This is such a technique that the sound field inside a closed curved surface can be completely controlled if a speaker array is configured, and a sound pressure having the closed curved surface shape which does not include a sound source and a particle velocity in the normal direction can be completely controlled. When using the sound field reproduction technique which uses wave field synthesis, the sound field inside the closed curved surface is completely reproduced and the degree of freedom of the listening position is also increased.
For example, in PTL 1, a three-dimensional sound field reproduction device is disclosed in which a plurality of speakers of the speaker array cover the entire head of the listener and a high level of realism can be reproduced. However, in the three-dimensional sound field reproduction device, since the plurality of speakers are used and to configure the array is needed, there is a problem that the scale becomes large. In addition, in a case of using the speaker array, there is a problem in that the frequency band to be reproduced is limited by the distance between the speakers due to a problem of spatial aliasing.
On the other hand, in the field of headphone reproduction, there is a virtual surround sound using the head-related transfer function. When using the virtual surround, it is possible to ideally enjoy sound field with a handy headphone device and the problem concerning the listening position does not occur.